With increasing integration of semiconductor devices, channel lengths decrease continuously for MOSFETs. A series of effects that are negligible in a long channel model of the MOSFET become increasingly obvious, or even become dominant factors influencing performances of the devices. These effects are generally referred to as a short channel effect, which may deteriorate electrical performances of the devices. For example, the short channel effect may cause problems such as gate threshold voltage decrease, power consumption increase, and signal-to-noise ratio degradation, or the like.
Fully-depleted non-planar devices, such as Fin Field-Effect Transistors (FinFETs) are ideal for devices at 20 nm or even smaller dimensions. The FinFET is a novel design developed from conventional standard transistors, e.g., Field-Effect Transistors (FETs). In the FinFET, certain surfaces of a fin are used as a channel, whereby avoiding the short channel effect in the conventional transistor while increasing its working current.
Metal siliconization process of Ni or NiPt alloy is often used in manufacturing the traditional FinFET. As shown in FIG. 1, a Ni (Pt) silicide 110 is formed on a source/drain region to reduce a square resistance and an ohm contact resistance of the device. However, amorphous boundaries and dislocation lines 105 may be generated in a fin 102 during source/drain implementation and annealing. In the process of forming silicide, as shown in FIG. 2, Ni (Pt) ions 1701 diffuse along the dislocation lines 105 to form many discrete NiSi dots in a depletion region. When a voltage is applied, strong electric-field intensity is generated in the depletion region, causing conductive paths between these discrete dots. Consequently, a large leakage current flows toward the substrate, thereby degrading the performance of the device.